The present invention relates to a liquid crystal display device and a manufacturing method thereof. More particularly, it relates to a liquid crystal display device and a manufacturing method thereof which is capable of preventing display deficiencies owing to interference between a liquid crystal display panel and a backlighting unit (especially light guide plate) or between the former and a casing, and which is also capable of maintaining an uniform brightness for the backlighting unit.
Conventionally, liquid crystal display devices has been arranged with a backlighting unit 33 having a light guide plate 32 on a rear surface side of a liquid crystal display panel 31 as shown in FIG. 12 so that letters or images being displayed on the liquid crystal display panel can be clearly seen. Though not shown in the drawings, the liquid crystal display panel 31 and backlighting unit 33 are housed in the interior of the casing in a condition in which they are positioned by means of positioning covers.
As shown in FIG. 12, the liquid crystal display panel 31 is disposed in the front surface side of the light guide plate 32 being remote therefrom by a specified clearance with spacers 34 being interposed therebetween for cushioning. By the spacers 34, the liquid crystal display panel 31 can maintain a distance with respect to the light guide plate 32 and thus can be prevented from contacting the same.
The liquid crystal display panel 31 is so arranged that a spaced portion is formed by sealing peripheral edge portions of two flat transparent substrates 31a, 31b (which might be, for instance, made of glass) with a sealing member 31c, and liquid crystal (not shown) is enclosed into this spaced portion. A standard thickness for the transparent substrates 31a, 31b is approximately 0.7 to 1.1 mm.
The backlighting unit 33 is so arranged that an optical sheet such as a diffusing sheet and a reflective sheet (neither of them are shown in the drawing) are respectively adhered to or abutted against the front surface and rear surface of the light guide plate 32, and that a cold-cathode tube 35 is provided on a side surface of the light guide plate 32 to serve as a white color source.
In the liquid crystal display device as shown in FIG. 13 which is an example of a conventional liquid crystal display device having a frame and casing, a light guide plate 41 is housed in the interior of a frame 44 from a front surface thereof. The liquid crystal display panel 43 is disposed in the front surface side of the light guide plate 41 being remote therefrom by a specified clearance with spacers 47 being interposed therebetween for cushioning.
A frame 45 is disposed in the front surface side of the liquid crystal display panel 43 being remote therefrom by a specified clearance with spacers 48 being interposed therebetween for cushioning. The frame 45 covers an outer surface of the frame 44. Being supported by the frames 44, 45, the liquid crystal display panel 43 and light guide plate 41 are respectively positioned so as not to move in directions with respect to the surfaces, and are housed in the interior of a spaced portion surrounded by a casing of the display surface side 49 and a casing of the rear surface side 50.
The liquid crystal display panel 43 is so arranged that a spaced portion is formed by sealing peripheral edge portions of two flat glass substrates 43a, 43bwith a sealing member 43c, and liquid crystal (not shown) is enclosed into this spaced portion. In order to bond the two glass substrates 43a, 43b by compression, thermosetting resin is applied onto a peripheral edge portion of a surface of either of the opposing surfaces of the glass substrates 43a, 43b, and four corners of the opposing surfaces of the glass substrates 43a, 43b are temporally fastened by using, for instance, UV curable resin. Thereafter, the glass substrates 43a, 43b are bonded through thermal compression wherein they are disposed on a surface plate which has been heated to approximately 100 to 180.degree. C. and are applied with pressure.
Recently, liquid crystal display devices which are employed for notebook personal computers are required to be increasingly light-weighted, thin-sized, and low power consumption type, and very thin type liquid crystal display devices with a thickness of approximately 5.0 mm have been manufactured. There are known various methods for achieving thin-sizing such as eliminating covers for positioning or making transparent substrates thin. In these days, there have been manufactured liquid crystal display devices of very thin size which include thin and light-weighted light guide plates and transparent substrates. Especially the thickness of transparent substrates 31a, 31b that play a large role in whether light-weighted and thin-sized type products can be achieved are being decreased to approximately 0.5 to 0.6 mm.
However, in such very thin-sized liquid crystal display devices, there are employed liquid crystal display panels 31, 43 as shown in FIGS. 12 and 13 which are very thin and are apt to bending owing to their own weight. Simultaneously, spaces between the liquid crystal display panels 31, 43 and the backlighting unit 33 are also very narrow (see gaps G11, G12 between the liquid crystal display panels 31, 43 and the light guide plates 32, 41 in FIGS. 12 and 13). Therefore, the liquid crystal display panels 31, 43 are apt to partially contact the backlighting unit such as the light guide plates 32, 41 or other members such as the casing due to undulations in the light guide plates 32, 41 or bending in the transparent substrates 31a, 31b, 43a, 43b, and might consequently result in display deficiencies (so-called paddling) owing to interference. For instance, in case the liquid crystal display panels 31, 43 contact other members, gaps between substrates which enclose liquid crystal therein are varied and display deficiencies such as formation of wave-like patterns are generated.
Further, in case the liquid crystal display panels 31, 43 contact the backlighting unit 33, there might be generated wrinkles in sheets such as the diffusing sheet in the front surface side of the light guide plates 32, 41 which constitute the backlighting unit 33, and these wrinkles might cause partial darkening of light of the backlighting unit 33.
The present invention has been made to solve these problems, and it is an object of the present invention to provide a liquid crystal display devices and a manufacturing method thereof which is capable of preventing display deficiencies owing to interference between a liquid crystal display panel and a backlighting unit (especially light guide plate) or between the former and a casing, and which is also capable of maintaining an uniform brightness for the backlighting unit.